All Natural Stacks ingredients are selected solely on the basis of their quality and purity. They only select the most bioavailable ingredients - meaning that you reap the full benefit of each and every product. Natural Stacks formulas are free from all GMOs, artificial colours, artificial flavours, and gluten. The capsules are vegetarian-friendly and allow optimal absorption of each product. They believe that quality is everything. It is the single most important factor in all their decisions, from what ingredients they purchase, to how they combine them and deliver them to you.